The links to register an application under the Paypal Chained payments setting in Network Settings do not work
"You must register this application with PayPal using your business account login to get an Application ID that will work with your API credentials. A bit of a hassle, but worth it! In the near future we will be looking for ways to simplify this process. Register then submit your application while logged in to the developer portal. Note that you do not need an Application ID for testing in sandbox mode. More Information »"